See Verbum CWL 2:146-47 for Thomas insight and violence… connected, in fact, with pati!
“On the other hand, as soon as the theory of God moving the will to the act of willing the end was proposed, Aquinas immediately perceived a difficulty; that difficulty to a modern Scholastic would be in all probability that man must be the efficient cause of his own operation, action, act, willing; but to Aquinas the difficulty was that the act must be not violent but natural; he noticed it both in the De malo and in the Prima secundae, and his answers run as follows:
… the will contributes something when it is moved by God; for it is the will which operates, but moved by God; and therefore its movement, though it be from outside as from a first principle, is nevertheless not violent. [De malo, q. 6, a. 1, ad 4m.]
… it does not suffice for the note of violence, that the principle be external, but one must add that the receiver of the influence make no contribution (to the operation). And this is not the case when the will is moved by an external agent; for it is the will that wills, though moved by something else. [STh 1-2, q. 9, a. 4, ad 2m; see ad 1m and 3m; see also q. 6, aa. 4 and 5 (esp. a 4, ad 2m).]
Now what does the patient, the will moved by God, when it is moved by God, while it is moved by God, confer or contribute? It operates. It wills. In this case the operation is an operatio receptiva, just as sentire is a pati of sense and just as intelligere is a pati of the possible intellect. The will operates inasmuch as it is the will that is actuated. The will contributes inasmuch as an act received in the will has to be a ‘wiling,’ not because it is act, nor merely because of the extrinsic mover, but proximately because act is limited by the potency in which it is received.”